The present invention relates to a pulley pressure control system for a transmission which controls a pressing force and an elastic force applied stabilize torque and achieve high efficient transmission, which is applicable to general industrial machines, vehicles, electric motors and the like.
A constant horse power transmission is known from U.S. Pat. Nos. 4,973,288 and 5,269,726; the former discloses a hydraulic type and the latter a screw pressurizing type. The inventive concepts of both the patents have a principal defect. FIGS. 1(A) to 1(F) are views of assistance in explaining the principle of transmission in a belt type transmission. The figures show in the order of (A) to (E) change-over-time of a belt 3 on a secondary pulley 2 when a primary pulley 1 supplies a speed reducing instruction to the secondary pulley 2. When a constant speed ratio shifts from xcex50 to xcex51, the contact radius of the belt 3 keeps a concentric circle; however, the belt 3 generates a skip motion at a final stage as shown the two figures (D) and (E). More specifically, at this time, a gap 3xe2x80x2 is created between the belt and the pulley, with the result of which the application of pressure is instantaneously stopped as shown in FIG. 1(F). The quality of stable transmission in the belt type transmission depends on whether or not appropriate frictional force can be automatically recovered momentarily after the skip motion. In addition, also the quality of quick responsibility depends on the same. The belt type transmissions proposed by the above patents disclose cam compensation; however, the cam is recovered due to the release of pressure upon the skip motion, resulting in inappropriate operation. On the other hand, even if the transmission is artificially controlled only by a pressing force with the use of an automatic control system that involves a time delay inherently, it is realistically impossible to recover the appropriate frictional force momentarily, so that the quick responsibility will not be attained.
The present applicant has proposed in U.S. Pat. No. 6,120,400 frictional force control with the use of an elastic body and the division of roles of pulley function. The pulley function includes a reference pulley function and a follower pulley function by discriminating a pressing force and an elastic force respectively. To be more specific, the reference pulley function implements a rotation speed control and positioning a belt with the pressing force. The follower pulley function implements a torque control by application of frictional force of the elastic force. However, there remain some outstanding problems. First, although the follower function side is able to control the elastic force, the reference pulley function side has only the pressure as a control element, so that the frictional force supplied to the reference pulley function side cannot be positively controlled. Consequently, a shaft torque control cannot be performed sufficiently. On the other hand, the follower pulley side does not include the rotation speed control element, which leads to the same problem. Second, transmission efficiency deteriorates at both end ranges of a speed change range. That is, the transmission efficiency can not be averaged over the entire speed change range, which leads to narrowing an actual speed change range. Since transmission capacity of the belt type transmission will be determined by the product (Nxc3x97T) of a rotation speed N and torque T for each pulley, the first problem is essentially the same as second problem. Accordingly, it is possible to solve the second problem if the first problem can be solved. More specifically, the control elements of the rotation speed and the shaft torque are configured to be independently adjustable for each pulley. In other words, a regulating function is divided into a function for regulating the rotation speed and a function for regulating the torque. This achieves high accuracy and high efficiency in the transmission.
Accordingly, it is a general object of the present invention to provide a pulley pressure control system for a transmission, in which a pressing force and/or an elastic force are individually arbitrarily regulated from outside for each pulley and applied to the same, and a pulley role function (function by role) and a control factor regulating function (function by element) are separately controlled.
A first object of the present invention is to provide a pulley pressure control system capable of independently selecting and applying a pressing force and/or an elastic force to a single pulley, and externally regulating the pressure and/or elastic force to arbitrary values independently.
A second object of the present invention is to provide a pulley pressure control system capable of applying an elastic force to a pulley having a follower pulley function based on a rotation speed element relating to the speed change displacement of a movable disk and a torque element relating to the compressive displacement of an elastic body, both the elements being adjustable independently.
A third object of the present invention is to provide a pulley pressure control system capable of independently applying a pressing force, an elastic force and a semi-elastic force, to a single pulley, the elastic vibration of which is restrained by the simultaneous supply of the pressing force and the elastic force to the pulley.
A fourth object of the present invention is to provide a pulley pressure control system in which a channel of a pressing force is different from a channel of an elastic force each led to a single pulley, and switching instructions between pulley role functions to the channels are provided so as to achieve a role function and an element-by-element function.
A fifth object of the present invention is to provide a pulley pressure control system capable of simultaneously applying a pressing force and a semi-elastic force, the elastic vibration of which is substantially restrained by the pressing force, to a pulley having a reference pulley function, and giving the pulley a frictional force regulating function with high efficiency and high accuracy so as to eliminate a slip and braking during transmitting operation.
A sixth object of the present invention is to provide a pulley pressure control system capable of controlling, by a single control unit, a regulating function by control element relating to a rotation speed and torque, and a switching function of pulley roles relating to a reference pulley and a follower pulley.
A seventh object of the present invention is to provide a pulley pressure control system capable of performing a function by element and a function by role for compensating an error such as various kinds of deformation and deterioration in transmitting members and transmission ability such as efficiency, and speed-change regulation and torque regulation, based on four control elements including a rotation speed and torque by using pressure application devices each disposed for a pulley of a transmission.
An eighth object of the present invention is to provide a pulley pressure control system capable of synchronously switching between two pulley role functions at an arbitrary point of time whatever a transmission is in operation or in halt, or operation is performed artificially or automatically, selectively controlling optimum transmission ability, and, in particular, realizing an inexpensive system with high efficiency irrespective of whether a transmission is of a press-belt type or pull-belt type.
A ninth solving means according to the present invention is to provide a pressure control system composed by assembly with two types of pressure application devices whereby a pressing force and a elastic force and wishably applied to a movable disk of a singular pulley.
A tenth solving means according to the present invention is to provide a pressure control system preceding one of a pressing force and an elastic force to give one of input and output pulleys and simultaneously the other of the forces to give the other pulley so as to be capable of switching the role of each pulley function.
A eleventh solving means according to the present invention is to provide a pressure control system externally controlling axial torque on both sides of input and output pulley shafts by way of regulating separately each friction forces to the pulleys using the control means.
A twelfth solving means according to the present invention is to provide a pressure control system externally controlling a rotating speed of a output pulley using the control means in a manner that one of the pressing forces in input and output pulleys is preceded as an actual state and the other to be treated as a reserved state.
A general solving means according to the present invention is to provide a pulley pressure control system for a transmission in which a pressing force supply path and an elastic force supply path are disposed in parallel with each other, which pressing force supply path is directly led to a pulley through one of two pressing ends of a compound compressing device and which elastic force supply path is indirectly led to the pulley through the other of the two pressing ends and an elastic body, and elements of a rotation speed and torque are switched between and then individually regulated.
A first solving means according to the present invention is to provide a pulley pressure control system in which a pressing force supply path for a pressing force and an elastic force supply path for an elastic force are disposed in parallel with each other for a single pulley, an instruction is issued through either one of or both the pressing force supply path and the elastic force supply path to regulate the pressing force and/or the elastic force to zero or an arbitrary value for selecting a type of pressure.
A second solving means according to the present invention is to provide a pulley pressure control system in which a movable disk and an elastic device are independently regulated by a compound compressing device having an superposing pressing end that receives both amounts of displacement of two pressing devices and a non-superposing pressing end that receives a non-superposed amount of displacement of the two pressing devices.
A third solving means according to the present invention is to provide a pulley pressure control system in which a pressing force supply path for a pressing force and an elastic force supply path for an elastic force are disposed in parallel with each other for a movable disk, and the pressing force, the elastic force, and a semi-elastic force are individually applied to the movable disk through the pressing force supply path or the elastic force supply path by means of an engagement device that interrupts transmission of one of the pressing force and the elastic force.
A fourth solving means according to the present invention is to provide a pulley pressure control system in which a function by element and a function by role are individually controlled by supplying an instruction to switch between pulley role functions through a pressing force instruction supply path and an elastic force instruction supply path.
A fifth solving means according to the present invention is to provide a pulley pressure control system in which pressure is simultaneously transmitted to a movable disk through both a pressing force supply path and an elastic force supply path disposed in parallel with each other, whereby a semi-elastic force is controlled by a control unit over an entire or a partial speed-change area.
A sixth solving means according to the present invention is to provide a pulley pressure control system in which a control unit that performs a regulating function by element, that is, a rotation speed and torque, supplies to a pulley a switching instruction of function by role, that is, a reference pulley and a follower pulley, whereby the pulley performs the reference pulley and the follower pulley distinguishably.
A seventh solving means according to the present invention is to provide a pulley pressure control system in which a pressure application device is provided for respective pulleys of a transmission, instructions are supplied through four driving sources and four instruction supply paths to the pressure application devices synchronously or asynchronously to compensate a driving pulley and a driven pulley independently for various factors to be regulated in addition to speed-controlling and torque-controlling, and thereby artificially creating an optimum transmission state.
An eighth solving means according to the present invention is to provide a pulley pressure control system in which a function switching instruction is issued through an instruction supply path of each pressure application device to synchronously switch between operation modes, a forward mode and a reverse mode in a transmission based on a position of a belt at an arbitrary speed ratio, a rotation speed or the like.